This invention relates generally to a vertical discharge slot diffuser utilized to reduce the effect of large heat losses through walls, windows and the like, and more particularly to a diffuser that requires only a small quantity of air to counteract such thermal leakage.
When a low outside temperature exists, it is not uncommon for the average heat loss through the walls and windows of a building to exceed 400 BTUs per linear foot. Attempts to lower the rates of heat loss have included conventional perimeter air distribution systems which blow hot air introduced at the ceiling away from the wall to induce cold air in an upward direction. With greater wall losses, the usual practice is to utilize a distributing unit that directs warm air upwardly from the floor or from a soffit located beneath the window. The primary problem associated with existing floor mounted units is that a large volume of air is needed in order to effectively counteract the high rate of thermal leakage which can in turn result in excessive operating costs.
It is frequently undesirable to mount a unit on the floor because the ductwork must penetrate the floor slab and a high installation cost sometimes results. Therefore, distribution systems have been developed that utilize a plurality of ceiling mounted diffusers to direct warm air downwardly. Again, however, such systems require a large volume of air to effectively offset large wall losses. Furthermore, diffuser systems produce a weak Coanda effect and the air flowing from the diffuser does not properly hug the wall, thereby creating drafts of warm air that cause discomfort to persons in the room.
To overcome these problems, this invention is adapted to be either sill mounted or mounted above the false ceiling of the room, where it may be easily installed and where it does not occupy valuable space within the room. In addition, since the diffuser is located adjacent to a wall, the blanket of air produced tends to hug the wall. This wall attachment principle, known as the Coanda effect, is well known in the science of fluidics or fluid logic and is particularly useful in air circulation systems. The utilization of a continuous, vertically directed slot results in the maximum Coanda effect, thereby causing the air curtain to remain near the wall so as not to produce undesirable drafts in the occupied part of the room.
An important advantage of this invention is that it effectively counteracts high rates of heat loss while requiring only a small quantity of hot air. Accordingly, the attached ducts may be relatively small and installation costs are therefore substantially reduced. Since the diffuser discharges air at a velocity more than twice as great as the velocity from conventional diffusers, the hot air from the diffuser is much more rapidly mixed with the cold air adjacent to the wall or window. The rapid mixing process thereby obtained allows a small amount of air to be introduced at a high temperature, resulting in a high induction ratio--approximately 1 cubic foot of air from the diffuser mixes with 4 cubic feet of room air to effectively counteract a high rate of heat loss. Moreover, if the diffuser is mounted on the ceiling, the heat from the introduced air is dissipated before reaching the occupied area near the floor, and the resulting air mixture approaches room temperature prior to contacting the occupants of the room. Therefore, any discomfort caused by warm air currents is avoided.
It should also be noted that the slot air construction utilized herewith creates a downward or upward flow in a vertical direction with a minimum amount of turbulence being imparted to the discharged air. As a result of the novel streamlined slot construction, the noise is minimized while at the same time a space is provided for the induced air to curl back into the high velocity low volume discharge and deposit any dirt in the induced air on the diffuser rather than on the adjacent ceiling or sill.
A primary object of this invention is to counteract heat leakage through walls, windows and the like by providing an air diffuser that requires a relatively small quantity of air to effectively perform its function. This feature is achieved by discharging high temperature air from the diffuser at a high velocity to produce a rapid intermixing of the hot air with the cold air leaking into the room.
Another primary object of the invention is to provide a diffuser of the character described that operates relatively noiselessly.
Yet another object of this invention is to provide a diffuser of the character described that has a vertically directed discharge slot located adjacent a wall or window so as to obtain maximum advantage from the Coanda effect.
A further object of this invention is to provide a diffuser of the character described that may be mounted on either the ceiling or sill and discharge air vertically either downwardly or upwardly.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.